Screed compensating and adjusting means



Dec. 1, 1959 H. c. POLLITZ 2,914,994

SCREED COMPENSATING AND ADJUSTING MEANS Filed March 18, 1957 2Sheets-Sheet 1 INVENTOB.

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Dec. 1, 1959 H. c. POLLlTZ SCREED COMPENSATING AND ADJUSTING MEANS FiledMarch 18, 1957 2 Sheets-Sheet 2 SCREED COMPEN SATIN G AND ADJUSTINGMEANS Harold C. Pollitz, Cedar Rapids, Iowa, assignor to Iowa suitablemix. The mixis delivered by a rearwardly travel Manufacturing Company ofCedar Rapids, Iowa, Cedar Rapids, Iowa, a corporation of Iowa Thisinvention relates to road surfacing machines which employ a screed forlevelling and'l finishing the bed of surfacing material, and has to dowith compensating means for accommodating expansion and'contraction ofthe screed plate while assuring that it is maintained flat and incontact throughout 'its'area with the surface of the bed of surfacingmaterial, or bowed for crowning, as the case may be.

Road surfacing machines of the above character are well known and ratherextensively used. lnsuch machines the screed plate is heated, by knownmeans, to a rather high temperature, which is necessary to impart theproper finish to the top of the bed of surfacing material. When thescreedplate is heated it expands and when its temperature is lowered toappreciable extent, in its passage over the surface material, itcontracts. The resultant expansion and contraction of the screed platefrequently causes substantial lengthwise warping or buckling thereofsuch that appreciable areas of the plate do not remain-in contact withthe surfacing material. That renders it difficult to obtain the properfinish of the surface of the material and necessitates slowing down ofthe rate of travel of the machine in anendeavor to overcome thatdifficulty, with resultant slowing down of the road surfacing operation,which is objectionable for obvious reasons.

My invention is directed to means for avoiding the above noteddifliculty in respect to screeds as presently used in road surfacingmachines. To that end I provide compensating means whereby expansion andcontraction of the screed plate, in accordance with variations intemperature'thereof, is accommodated and warping or buckling of theplate is prevented. More particularly I provide compensating andadjusting levers attached to the screed plate andadjusting meanstherefor so arranged that the plate isv free to expandand contractlengthwise and is effectively restrained against lengthwise buckling orwarping, such levers also providing means for adjusting the screed platefor crowning. Furtherobjectsj and advantages of my invention will appearfrom the detail description.

In the drawings: Figure 1.isa side view of'a road surfacing machineincluding a screed comprising screed plate compensating and adjustingmeans embodying my invention;

Figure 2 is aplan'view of the screed assembly and associated parts,certain parts being broken away and certain other parts being omittedfor clearness of illustration; and p Figure 3 is a sectional View takensubstantially on line 3-3 of Figure 2, certain parts being shown inelevation and certain other parts being shown rather diagrammatically.

My present invention is'in the nature of an improvement over the screeddisclosed in' my Patent No. 2,757,- 588, granted August 17, 1956, forVibrating Finishing Machine; 1 r

The machine of Figure 1 includes. a. tractorSrand a 2,914,994 PatentedDec. 1, 1959 10; the unit as a whole being self-propelled along a roadbeing surfaced. The hopper 6 receives the road surfacing mix, which maybe bitumen and an aggregate, or any ling conveyor (not shown) to a twopart screw conveyor or distributor 11 which spreads the mix upon theroadway in front of a deflector plate 12. The plate 12 is disposed infront of and deflects the mix downward and rearward to, a screedassembly 13 supported by arms 14 pivoted at their forward ends, at 15,to the tractor unit and extending rearwardly therebeyond. The machine sofar described, including the screed assembly 13, is similar to that ofmy above identified patent.

The screed assembly 13, in general, may be of any suitable construction.It is supported at its front from arms 14 by links 16 pivoted at theirupper ends in brackets 17 secured to and depending from arms 14 andpivoted at their lower ends in brackets 18 secured to assembly 13. Atits rear the screed assembly 13 is provided with split socket blocks 19secured to each end thereof. The blocks 19 receive balls 20 at the lowerends of adjusting screws 21 threaded through balls 22 mounted in splitsocket blocks 23 bolted to the rearward ends of arms 14. Each ball 22 isprovided with a rearwardly extending stud 24 projecting through a slot25 in block 23 effective for restraining ball 22 against turningmovement while permitting tilting thereof both lengthwise andtransversely of the screed assembly 13. A hand wheel 26 is fixed on theupper end of each screw 21, which also has secured thereon a disc 27disposed below hand wheel 26 and cooperating with a suitably graduatedplate 28, mounted on block 23, to indicate the extent of verticaladjustment of the corresponding end of the screed assembly 13. Each ofthe adjusting screws 21 is further provided with a ratchet wheel 29secured thereon a short distance above block 19. A locking pawl 30 ispivoted in a bracket 31 secured to the screed assembly 13, adjacent eachratchet wheel 29 and normally is held in engagement therewith bysuitable means, such as a compression spring 32. As will be understoodfrom the above, the screed assembly 13 may be adjusted, by means of thescrews 21, so as to dispose the screed plate 33, at the underneath ofthe assembly either horizontally for contact with the bed of surfacingmaterial, when the bed is to be of uniform thickness, or at aninclination lengthwise for crowning, when the bed is to be ofconsiderable width and of decreasing thickness from the center of theroadway toward the sides thereof, as is known.

The screed plate 33 is formed of camparatively thin resilient platemetal, is flat and of substantially rectangular shape in plan, and maybe, by way of example, approximately ten feet long and two feet wide. Itis provided with upwardly extending front and rear flanges 34 and 35 andis suspended from screed assembly 13, as shown more clearly in Figure 3,by means of resilient hangers 36 of substantially inverted L shape, thearms of which are members 38 of the assembly 33. The hangers 36 suspend.

the screed plate 33 from the screed assembly 13 for vertical adjustmenttherewith, and the elements 37 of hangers 36, being resilient, avoid anyobjectionable interference with vertical vibration of the screed plate33 independently of screed assembly 13, by means to be describedpresently. End plates 39 are mounted on the screed assembly 13, freefrom plate 33 so as not to interfere with freedom of vibration oradjustment thereof. The plate 33 may be heated from its upper side bysuitable known means, such as an oil burner 40 from which the hotprodnets of combustion are directed downward by a stack 41 and areuniformly distributed, by suitably disposed ducts and baflles, over theupper face of screed plate 33, as is known.

The screed plate 33 is vibrated in a suitable manner, preferably by aplurality of electro-magnetic vibrators 42 mounted on a cross member 43of the assembly and enclosed in housings 44 suspended from a channel member 45a supported above cross member 43 by boxings 46a. Each of thevibrators 42 has a tubular rod or armature 47a attached thereto at itsupper end and secured at its lower end, conveniently by welding, to theupper face of screed plate 33. The vibrators 42 are spaced uniformlyalong the screed assembly 13 lengthwise thereof and are suitablyenergized, preferably in the manner dis? closed in my above identifiedpatent, for vibrating the screed plate 33 vertically in the manner andfor the purposes stated in that patent. Within the broader aspects of myinvention, the screed plate 33 may be vibrated in any suitable manner.

The screed plate 33 is provided adjacent the front and the back thereofwith a pair of substantially L-shaped temperature compensating andadjusting levers 45. The shorter arm 46 of each lever 45 is pivoted at47 to a bracket 48 suitably secured, conveniently by welding, to theupper face of screed plate 33 adjacent the midlength thereof. The longerarm 49 of each lever 45 is pivoted at 50 between the upper ends of twolinks 51 disposed at opposite sides thereof and at opposite sides of abracket 52 suitably secured, conveniently by welding, to the upper faceof screed plate 33 a short distance from the end thereof, to whichbracket 52 the lower end of the links 51 are pivoted at 53. Asubstantially U-shaped bracket 54 is secured, conveniently by welding,to the upper face of arm 49 of each of the levers 45, adjacent the innerend thereof. A suitably bored and threaded block 55 is disposed betweenthe sides of bracket 54 and is pivoted by studs 56, at its oppositesides, in bracket 54 for turning movement about a horizontal axisextending transversely of screed plate 33. The blocks 55 of each pair oflevers 45 receive the threaded end portions of a turn-buckle 57.

The levers 45 of each pair are tied together at their inner ends by theturnbuckles 57 and associated parts and may be adjusted thereby toassure that the screed plate 33 is flat and level lengthwise as well astransversely. The linkage connections between the outer ends of thelevers 45 and the screed plate 33 accommodate expansion and contractionof the latter, due to temperature variations, and, in conjunction withlevers 45, effectively restrain the end portions of plate 33 againstvertical movement relative to the midportion thereof. That prevents anyobjectionable lengthwise warping or buckling of screed plate 33. Whenthe bed of surfacing material being laid is of substantial width,approximately twice the length of screed plate 33, for example, crowningmay be effected by disposing the screed plate 33 at an appropriateinclination lengthwise, by means of the adjusting screws 21, as abovedescribed. If the bed of surfacing material being laid is of a widthwithin the length of the screed plate 33 the latter may be bowedlengthwise to give the desired crown. That is accomplished by turningthe turn-buckle 57 in such direction as to force the inner ends of thelevers 45 of each pair thereof away from each other, it being noted thateach of the flanges 34 and 35 is provided at its midlength with avertical slot 58 extending for the full height thereof and thuscomprises two.

sections. Forcing the inner ends of levers 45 apart causes them to swingin opposite directions about pivots 47. That swings the outer ends oflevers 45 downward dc pressing the ends of screed plate 33 and impartingthere: to a lengthwise bow, determined by the extent of adjustment ofthe turnbuckles 57, for imparting the desired crown to the bed ofsurfacing material being laid. When the screed plate 33 is thus bowed,the levers 45 remain effective for preventing objectionable warping orbuckling thereof as before. The rear turnbuckle 57 and the hand wheels26 of the adjusting screw 21, and the locking pawls 30 are readilyaccessible from an operators platform 59 mounted at the back of thescreed assembly 13 on brackets 60, and a suitably disposed platform (notshown) may be provided giving ready access to the front turnbuckle 57.

It will be understood that changes in detail may be resorted to withoutdeparting from the field and scope of my invention, and I intend toinclude all such variations, as fall within the scope of the appendedclaims, in this application in which the preferred form only of myinvention has been disclosed.

I claim:

1. In a road surfacing machine, a support, a screed assembly mounted onsaid support, a substantially rectangular normally flat continuous andflexible screed plate suspended from said assembly for relative verticalvibration, means attached to said plate for vibrating it vertically andindependently of said assembly, means for heating said plate, a pair ofvertically and oppositely disposed rigid levers of substantially L-shapeextending lengthwise of said plate and pivoted thereto at their innerends adjacent the midlength of said plate, substantially verticallydisposed rigid links respectively having one end pivoted at a fixedpoint lengthwise thereof to said levers and their other end pivoted at afixed point lengthwise thereof to said plate adjacent the ends of thelatter, and means rigidly securing the inner ends of said levers inspaced relation above the pivots thereof, said links accommodatingexpansion and contraction of said plate and in cooperation with saidlevers restraining said plate against buckling incident to heatingthereof.

2. In a road surfacing machine, a support, a screed assembly mounted onsaid support, a substantially rectangular normally flat continuous andflexible screed plate suspended from said assembly for relative verticalvibration, means attached to said plate for vibrating it vertically andindependently of said assembly, means for heating said plate, a pair ofvertically and oppositely disposed rigid levers of substantially L-shapeextending lengthwise of said plate with the lower ends of their shorterarms pivoted to said plate adjacent the midlength thereof, substantiallyvertically disposed rigid links respectively having one end pivoted at afixed point lengthwise thereofto said levers adjacent the outer ends ofthe. longer arms of said levers and their other end pivoted at a fixedpoint lengthwise of said links to said plate adjacent the ends of thelatter, and means rigidly securing the shorter arms of said levers inspaced relation above the pivots thereof, said links accommodating exvpansion and contraction of said plate and in cooperation with saidlevers restraining said plate against buckling incident to heatingthereof.

3. In a road surfacing machine, a support, a screed assembly mounted onsaid support, a substantially rectangular normally flat continuous andflexible screed plate suspended from said assembly for relative verticalvibration, means attached to said plate for vibrating it vertically andindependently of said assembly, means for heating said plate, a pair ofvertically and oppositely disposed rigid levers of substantially L-shapeextending lengthwise of said plate with the lower ends of their shorterarms pivoted to said plate adjacent the midlength thereof, substantiallyvertically disposed rigid links respectively having one end pivoted at afixed point lengthwise thereof to said levers adjacent the outer ends ofthe longer arms of said levers and their other end pivoted at a fixedpoint lengthwise of said links to said plate adjacent the ends of thelatter, and means rigidly and adjustably securing the shorter arms ofsaid levers in spaced relation abovethe pivots thereof, said linksaccommodating expansion and contraction of said plate and in cooperationwith said levers restraining said plate against buckling incident toheating thereof, said securing means being effective for moving theinner arms of said levers apart and depressing the outer ends of saidlevers for optionally bowing said plate lengthwise.

4. In a road surfacing machine, a support, a screed assembly mounted onsaid support, a substantially rectangular normally flat and flexiblescreed plate suspended from said assembly for relative verticalvibration, means for vibrating said plate vertically and independentlyof said assembly, means for heating said plate, a pair of substantiallyvertically and oppositely disposed substantially L-shaped rigid leversextending lengthwise of said plate with the lower ends of their shorterarms pivoted to said plate adjacent the midlength thereof, substantiallyvertically disposed rigid connectors pivoted at fixed points lengthwisethereof to the longer arms of said levers adjacent the outer ends ofsaid longer arms and to said plate adjacent the ends thereofrespectively, and means rigidly and adjustably securing the upper endsof the shorter arms of said levers in spaced relation, said connectorsaccommodating expansion and contraction of said plate and in cooperationwith said levers restraining said plate against buckling incident toheating thereof; said securing means being elfective for moving theinner arms of said levers apart and depressing the outer ends of saidlevers for optionally bowing said plate lengthwise.

5. In a road surfacing machine, a support, a screed assembly mounted onsaid support, a substantially rectangular normally flat and flexiblescreed plate suspended from said assembly for relative verticalvibration, means for vibrating said plate vertically and independentlyof said assembly, means for heating said plate, a pair of substantiallyvertically and oppositely disposed substantially L-shaped rigid leversextending lengthwise of said plate adjacent each lengthwise edge thereofwith the lower ends of their shorter arms pivoted to said plate adjacentthe midlength thereof, substantially vertically disposed rigidconnectors pivoted at fixed points lengthwise thereof to the longer armsof said levers adjacent the outer ends of said longer arms and to saidplate adjacent the ends thereof respectively, and screw means rigidlyand adjustably securing the upper ends of the shorterarms of said leversin spaced relation, said connectors accommodating expansion andcontraction of said plate and in cooperation with said leversrestraining said plate against buckling incident to heating thereof,said securing means being effective for moving the inner'arms of saidlevers apart and depressing the outer ends of said levers for optionallybowing said plate lengthwise.

6. In a road surfacing-machine, a support, a screed assembly mounted onsaid support, a substantially rectangular and normally flat one piecescreed plate suspended from said assembly, means for heating said plate,a pair of rigid substantially vertically and oppositely disposedsubstantially L-shaped levers extending lengthwise of said plate andpivoted thereto at their inner ends, substantially vertically disposedrigid connectors pivoted at fixed points lengthwise thereof to saidlevers and to said plate adjacent the ends thereof respectively, andadjustable means rigidly securing the inner ends of said levers inspaced relation above the pivots thereof and effective for adjustingthem toward and away from each other about their pivot connections tosaid plate, said levers and connectors restraining said plate againstbuckling incident to heating thereof and said connectors accommodatingexpansion and contraction of said plate.

7. In a road surfacing machine, a support, a screed assembly mounted onsaid support, a substantially rectangular and normally flat screed platesuspended from said assembly, means for heating said plate, a pair ofsubstantially vertically and oppositely disposed rigid levers ofapproximately L-shape extending lengthwise of said plate with the lowerends of their shorter arms pivoted to said plate, substantiallyvertically disposed rigid connectors pivoted at fixed points lengthwisethereof to said levers adjacent the outer ends of the longer arms ofsaid levers and to said plate adjacent the ends of the latterrespectively, and means rigidly securing the inner ends of said leversin spaced relation above the pivots thereof, said levers and connectorsrestraining said plate against buckling incident to heating thereof andsaid connectors accommodating expansion and contraction of said plate.

References Cited in the file of this patent UNITED STATES PATENTS1,750,443 Tullis Mar. 11, 1930 1,987,398 Gardiner Jan. 8, 1935 1,995,450French Mar. 26, 1935 2,054,263 McCrery Sept. 15, 1936 2,092,458 KroutSept. 7, 1937 2,224,084 Mills et al. Dec. 3, 1940 r 2,271,333 FarrellJan. 27, 1942 2,351,593 Barber June 20, 1944 2,693,136 Barnes Nov. 2,1954 2,757,588 Pollitz Aug. 7, 1956

